Tundra and taiga are two biomes that exist in the far northern regions of the Earth. A biome is a region that is associated with particular climactic conditions and organisms that have adapted to live in those conditions.
Tundra
The arctic tundra, in the far northern reaches of the Earth, around the North Pole, is characterized by low temperatures and short growing seasons.
The angle of the sun's rays is always low in the tundra. Therefore, it never receives much energy from the sun at any time.
Summer
In the tundra, summer lasts six to eight weeks.
Summer days are very long. The long days allows enough heat from the sun to build up so that the upper layer of soil can thaw.
The lower layer of soil, known as the permafrost, is always frozen.
Because melting snow cannot drain into the permafrost, water collects on the surface.
Thus, in the summer, the tundra becomes covered in marshes and ponds.
During this short growing season, grasses and sedges become abundant. Low mats of lichens and mosses cover large areas.
Some trees, such as birches and willows grow close to the ground. They rarely grow more than a few centimeters tall.
The leaves of most plants are small. Flowers bloom and quickly develop seeds.
Arctic hares and arctic foxes can be seen in brown coats. (Their coats turn white in winter.)
Reindeer, also known as caribou, are plentiful.
Lemmings are also active.
Snowy owls and weasels, which prey on lemmings, can be seen when the lemming population is high.
Winter
When winter arrives, ponds and lakes freeze.
With short days and low temperatures, there is little energy available.
Food is scarce.
Living things become dependent on stored energy for survival.
Almost all tundra plants are dormant in winter.
Many insects remain in the egg or larval stage.
Reindeer migrate southward.
Many birds also travel south.
Lemmings and other small animals burrow under sheltered spots in the snow, where they consume seeds and parts of plants that they stored during the summer.
Taiga
The taiga is a broad band of coniferous forests that lies across Europe, Asia and North America.
It lies south of the tundra, and extends to about 50 degrees North latitude.
The southern part of the taiga is often called the Boreal forest.
The taiga receives more energy from the sun than the tundra.
Snowfall is heavier in the taiga than in the tundra.
The taiga is full of ponds and lakes that were formed by glaciers during the last ice age.
Most of the trees in the taiga forest are evergreen.
These trees block sunlight from reaching the ground all year round, so there is little vegetation near the ground.
Food production mostly takes places in the top parts of trees.
Young trees only have an opportunity to grow when the old forest is destroyed by fires or windstorms, allowing light to penetrate to the ground below.
When this happens, deciduous trees, which lose their leaves seasonally, such as birches and aspens, grow for a few years.
Then new conifers begin to grow underneath them.
Summer days are shorter in the taiga than in the tundra. However, in the taiga, it becomes warm enough during summer for the ground to thaw completely
During the summer, many insects attack the conifers, and in turn, many small birds eat the insects.
Some birds harvest conifers seeds.
A few mammals eat the needles and twigs of conifers.
Deer, elk and beaver live mostly live on the vegetation in ponds and along streams and riverbanks.
In the winter, a heavy blanket of snow protects plants that are low to the ground.
Conifer needles are protected with a waxy coating that reduces water loss when the ground is frozen and no liquid water is available.
Squirrels and bears sleep for long periods.
Insects hibernate, while the birds that eat them migrate southward.
Reindeer, which live in the tundra during the arctic summer, live in the taiga during the winter.
Lynxes, wolves and wolverines are active throughout the year. They prey on hares.